Sri Lanka remains in a violent limbo precariously close to war (Photos by Dushi Pillai)

The BBC's Nick Bryant visits north-east Sri Lanka, an area fast becoming a key battlefield as fears grow that troops and rebels are preparing to resume full-scale hostilities.

Our visit to Trincomalee was a tale of two journeys.

We were prevented from entering the port because our arrival coincided with a suspected Tamil Tiger grenade attack on a police checkpoint, which prompted the security forces to seal off the road.

Our departure was complicated by a virtual blockade of the city by the Janatha Vimukthi Peramuna (JVP), the extreme nationalist party, whose half-drunk supporters had surrounded our vehicle earlier that day and threatened to beat us up.

On the way in, we witnessed the ruthlessness of the rebels, who have come now to express themselves almost exclusively through violence and appear to be measuring their success in the blood of members of the security forces.

On the way out, we saw the brute force of Sinalese nationalism.

The attack on the police checkpoint was viewed by the security forces as almost routine - one of over 1,000 violations of the 2002 ceasefire agreement by the Tamil Tigers, the Colombo government alleges.

The suspected rebels waited until dark before hurling two grenades. One exploded metres short of the checkpoint, injuring a policeman. Another landed on the sandbag-protected bunker, but failed to detonate.

Then the checkpoint came under a hail of gunfire, a trademark of rebel attacks.

'Undeclared war'

We arrived a few minutes later, just after the army had launched their search for the suspected rebels. Two military motorbikes flashed by with gun-toting soldiers perched precariously on the back.

In an area dense with palm trees and undergrowth, and cloaked by now in almost complete darkness, their chances of success did not look good. Sure enough, they failed to flush out the attackers.

When we finally reached our hotel, the music in the lobby was a panpipe version of the Simon and Garfunkel classic Bridge Over Troubled Water.

Only five days before, the Sea Tigers had launched a suicide bomb attack on a Sri Lankan Navy patrol boat nearby in which 13 sailors were killed.

It seemed a particularly unfortunate choice.

Trincomalee, where Tamils, Sinhalese and Muslims are almost evenly split but the government is in control, is fast becoming a key battlefield in what feels more and more like an undeclared civil war.

Twenty-four hours after we arrived, the JVP started to enforce its three-day strike, which was called partly in protest at the recent upsurge in rebel violence.

'Mob rule'

Early that Thursday morning, we had set off from our hotel to meet up with the Sri Lankan army, who had promised to allow us to film one of their patrols.

The Sea Tigers are said to be well-armed and ruthless

But our way was soon blocked by a group of JVP strikers, who took great offence at our attempts to film the empty streets and barricaded shops.

As our vehicle was brought to an abrupt halt, we were quickly encircled. Some of the strikers covered their faces with scarves, one of them gripping a hacksaw in his right hand.

Others started making calls on their mobile phones to summon reinforcements.

One of the more thick-set protesters reached through the driver's window and seized control of the keys. Others threatened to harm our cameraman unless he handed over the tape - something which we refused to do.

Instead, we reluctantly agreed to erase a short portion of film - deleting enough to satisfy the strikers' drunken self-appointed censor, but retaining enough to give viewers a brief sense of the mob's violent intent.

The shots we didn't manage to capture were of the policeman standing in front of the vehicle and soldiers standing close by. Throughout the stand-off, they did nothing to intervene.

That day in Trincomalee the mob was in the chair.

Growing lawlessness

A few hours later, a major in the Sri Lankan army told us he could no longer guarantee our safety. There had been more JVP threats. Two hours later, we left.

Rajihar Manoharan's parents allege he was executed by military forces

The ceasefire agreement may not yet have broken down but there is an alarming level of lawlessness and unrestrained violence in the disputed north-east.

In Trincomalee alone, the Tigers are attacking at will. JVP hardliners can issue threats with impunity.

And the Sri Lankan military stands accused of the extra-judicial killing earlier this month of five young Tamil students, whom ceasefire monitors agree were shot through the head in execution-style killings.

By stepping up attacks, the Tamil Tigers clearly hope to provoke the government into a bloody retaliation so that the country's new president, Mahinda Rajapakse, will be blamed for the breakdown of the ceasefire.

Right now, the president says he remains committed to the truce.

There's little doubt that we will make further journeys to Sri Lanka over the coming months for the crisis seems almost certain to escalate. And there's little doubt those visits will be punctuated by violence and civil strife.

The government and the Tigers fully understand the dreadful consequences of a return to civil war.

But this is a country with a blood-soaked history, where reason has all too often given way to rage.